Royal Navy warships have been ordered to escort British-flagged vessels in the Persian Gulf, in the wake of the US killing of Iran’s top military leader.
Defence Secretary Ben Wallace said it would help protect ships and citizens amid fears Iran will seek revenge for the assassination of Qasem Soleimani.
Boris Johnson is due to return to the UK after a 12-day holiday and will talk to foreign leaders in the coming days.
Gen Soleimani was killed this week in a US drone strike in Baghdad, Iraq.
The killing of Gen Soleimani marks a major escalation in tensions between the US and Iran, with Tehran vowing to avenge his killing.
US President Donald Trump last night tweeted that the US will strike 52 Iranian sites “very fast and very hard” if Tehran follows through with its vow of revenge.
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Mr Wallace said HMS Montrose and HMS Defender will accompany UK-flagged ships through the Strait of Hormuz, as they did between July and November following the seizure of a British-flagged tanker by Iran.
He said he had spoken to his US counterpart, Mark Esper, on Friday and urged all parties to de-escalate the situation.
But Mr Wallace added: “Under international law the United States is entitled to defend itself against those posing an imminent threat to its citizens.”